Prof. Cohen and I answer six questions: (1) Why do we lock people up? (2) How can involuntary civil commitment be reconciled with people's constitutional right to liberty? (3) Why don't we treat homicide as a public health threat? (4) What is the difference between legal and medical approaches to mental illness? (5) Why is mental illness required for involuntary commitment? (6) Where are we in our efforts to understand the causes of mental illness?